Soil degradation and restoration

Current Issues in Soil Science

• Soil Degradation:

  • Definition: Change in soil health that impairs ecosystem services.

  • Causes: Decline in physical, chemical, biological quality due to inappropriate land use or management.

  • Main Initiators of Degradation:

    • Removal of protective vegetative cover

    • Overgrazing

    • Intensive cultivation

    • Deforestation

    • Industrial activities/Urbanization

Importance of Vegetative Cover

• Vegetative Cover Functions:

  • Shields soil from stress and erosion.

  • Provides anchorage through roots.

  • Acts as a source of organic matter, binding soil particles.

  • Enhances water infiltration.

Soil Modification by Humans

• Human Influence Factors: Soil order = f{Cl.O.R.P.T … H}.

• FAO Soil Classifications:

  • Anthrosol: Soils with intensive agricultural use and organic matter enrichment.

  • Technosol: Soils containing significant quantities of artifacts, often associated with urbanization.

Urbanization and Soil Sealing

• Increasing urban populations are projected to reach 66% by 2030.

• Urban Soil Characteristics:

  • High variability in structure and composition.

  • Often compacted with altered drainage and hydrology.

  • Presence of contaminants impacting nutrient cycles and biological activity.

Compaction Effects in Urban Areas

• Compaction leads to poor porosity and restricted drainage:

  • Ideal soil density: 1.1-1.4 g/cm3.

  • Compacted soils >1.7 g/cm3.

  • Impacts on runoff quantity and quality, surface ponding, and erosive potential.

Urban Watershed vs. Forested Watershed

• Comparison of water balance:

  • Forested watershed shows better infiltration and less surface runoff compared to urban watershed with impervious cover.

Soil Management Practices to Minimize Degradation

• Erosion Control Strategies:

  • Minimize exposed areas during construction.

  • Use techniques like silt fences, retention ponds, and low-impact development.

  • Implement porous paving and green roofs to enhance infiltration.

Agricultural Practices Leading to Soil Degradation

• Intensive Cultivation Methods:

  • Monocropping and aggressive tillage.

  • Reliance on chemical pesticides and fertilizers.

  • Water erosion remains a significant issue.

• Importance of crop rotation in maintaining soil health.

Role of Cover Crops

• Protect soil during off-seasons and enhance biodiversity:

  • Improve soil organic matter and structure.

  • Use deep-rooted crops to aid nutrient redistribution.

Tillage Practices Overview

• Types of Tillage:

  • Conventional tillage: most crop residue buried.

  • Conservation tillage: 30% crop residue retained.

  • No-till: direct seeding into previous residue.

• Implications for soil health and erosion prevention.

Desertification and Land Degradation

• Desertification: Extreme degradation in arid and semi-arid regions, connected to climate change and poor management practices.

• Affects 45% of Earth's land, exacerbating poverty.

Water Management and Soil Salinization

• Agriculture is a primary consumer of freshwater resources.

• Improper irrigation practices lead to salinization.

• Salinization defined as accumulation of water-soluble salts, can be natural or human-induced.

Chemical Contamination in Soils

• Types: Chemical contaminants include inorganic and organic sources from various sectors.

• Factors Influencing Fate of Contaminants:

  • Solubility, adsorption, and microbial breakdown potential.

  • Soil properties like clay content and organic matter affect leaching.

Glyphosate Usage and Soil Impact

• Glyphosate is the most commonly applied herbicide, known for its low toxicity to animals but extensive agricultural use.

• Contaminant behavior in soils influenced by chemical properties and pH interaction.

Conclusion on Soil Degradation Management

• Soil degradation impacts over 1/3 of global land area.

• Strategies exist for remediation, and understanding soil and contaminant interactions is key for effective management.